Ziegler-Natta catalyst systems are well known for their capability to polymerize olefins. They generally consist of a support which mostly is magnesium based onto which titanium component has been added along with organic compound known as internal donor. This catalyst when combined with co-catalyst and/or external donor comprise of the complete ZN catalyst system. Ziegler-Natta catalyst system which typically consists of transition metal halide normally titanium halide supported on metal compound which is typically magnesium dichloride. Along with transition metal, also there is organic component known as internal electron donor that plays a typical role during catalyst synthesis and polymerization. MgCl2 carrier, where the MgCl2 is in active form, can be created by various methodologies. One of the methods is precipitating the MgCl2 from an organic solution where magnesium is present as a soluble compound. The soluble magnesium compound can be achieved by starting from a magnesium alkyl and treating it with an alcohol. This step is then followed by chlorination of Mg alkyl or alkoxy compounds by a chlorination agent. The magnesium carrier can also be precipitated in the form of ‘ready-made’ MgCl2. In that case the MgCl2 has to be dissolved first in some suitable donor compound and then precipitated in hydrocarbon solvent. The MgCl2 support material can also be precipitated by chlorinating a soluble magnesium alkyl compound simply by treating it with chlorine gas or hydrochloric acid. Once the desired specification of carrier is obtained, this is generally followed by titanation procedure which finally results in the catalyst synthesis.
JPH0277406 describes catalyst capable of giving highly stereo-regular polymers having ordered shape, comprising a specific solid component containing Mg, Ti, alkyl monohalide, phthalic acid derivative and aliphatic alcohol, etc., Si compound and organoaluminum compound. The component A is prepared by the following process: a mixture comprising (1) a substrate formed by reaction, in the presence of iodine, between metallic Mg powder and two or more molar times of an alkyl monohalide and (2) a phthalic diester is grounded, and the resulting product is incorporated, in the presence of an aliphatic hydrocarbon, at ≧70° C., with a tetraalkoxytitanium, aliphatic alcohol and phthalic dichloride successively in this order to make respective treatments, and the resultant product is then incorporated with titanium tetrachloride to make a treatment. The component (B) is a Si component of the formula (R is alkyl, vinyl or aryl; R′ is alkyl; 0<=m<4), and component (C) an organoaluminum compound. The catalyst describe herein comprises of component A, B and C.
U.S. Pat. No. 7,220,694 relates to a magnesium compound effective in producing olefin polymers having an increased bulk density and a narrowed particle size distribution, without compromising on the stereospecificity of the polymers produced and the polymerization activity. The olefin polymerization catalyst comprises (A) a solid catalyst component prepared by contacting a magnesium compound having a specific particle size distribution index (P), a titanium compound and an electron donor compound with each other, (B) an organometallic compound, which is organoaluminum compound and (C) an electron donor which belongs to electron donors which are added to improve the stereospecificity of the olefin polymer during polymerization i.e. external electron donor.
U.S. Pat. No. 4,260,709 describes catalysts for use in the polymerization of olefins comprising compounds of magnesium and one or more transition metals of groups IVa, Va and VIa, which are at least partially reduced, with the catalysts being prepared by reaction of magnesium, at least one mono-halogenated hydrocarbon and a compound of a transition metal having a valence of at least 4. The catalysts can be used for the polymerization of olefins, such as ethylene, in the low-pressure process.
U.S. Pat. No. 4,379,898 describes polymerization catalyst preparation comprising of milling magnesium metal, an organic halide and titanium tetrahalide in the presence of a triaryl phosphite and an aluminum trihalide but in the absence of a complexing diluent. The titanium catalyst component is activated with an organoaluminum activator producing a catalyst for olefin polymerization.
The present art of Ziegler-Natta catalyst synthesis involves the usage of magnesium based compounds for the generation of active support. The magnesium based compounds are generally derived products of magnesium. The usage of metallic magnesium as such in the preparation of precursor is very limited.